This application is the U.S. National Phase under 35 U.S.C. xc2xa7371 of International Application PCT/JP98/05417, filed Dec. 2, 1998.
1. Field of the Invention
The present invention relates to a container for receiving and transporting an article such as a substrate necessary to be kept under the condition of high cleanliness during being transported. It is described hereunder in relation to a semiconductor substrate such as a silicon wafer or a liquid crystal substrate, in particular a silicon wafer as an example, however, the present invention is not limited to the above. The present invention is applicable to any article necessary to be kept under the condition of high cleanliness during being transported.
2. Background of the Invention
The semiconductor substrate, in particular silicon wafer is contaminated when dust or vaporized organic compounds (hereinafter simply referred to as xe2x80x9cdustxe2x80x9d) are attached thereto, thus leading to a lower productivity, i.e., the rate of producing a high-quality of product is low. It is therefore necessary to maintain high cleanliness in surrounding environment of the silicon wafer when the silicon wafer is transported. More specifically, the silicon wafer is one of the articles necessary to be kept under the condition of high cleanliness during transported (hereinafter referred to as xe2x80x9cdust free articlexe2x80x9d).
In general, the silicon wafer is worked in a room where cleanliness is high (hereinafter referred to as a xe2x80x9chigh cleanliness roomxe2x80x9d), i.e., so called a clean room. On the other hand, when the silicon wafer is transported in a room where cleanliness is low, the silicon wafer is received in a hermetically sealed container, the inside of which is kept under the condition of high cleanliness (hereinafter referred to as xe2x80x9ccontainerxe2x80x9d), and then, the container with the silicon wafer received therein is transported. Thus, the silicon wafer can be transported through a room in which the degree of cleanliness is low or outdoor (hereinafter referred to as xe2x80x9clow cleanliness roomxe2x80x9d), avoiding the silicon wafer from being contaminated during transported.
There is disposed a loader with an opening portion, which can be closed, in the border portion between the high cleanliness room and the low cleanliness room. The silicon wafer is transported through the above loader from the inner space of the container with high cleanliness to the high cleanliness room for working the silicon wafer or the like (hereinafter referred to as xe2x80x9cloadingxe2x80x9d), in addition, from the high cleanliness room to the inner space of the container with high cleanliness for transferring the worked silicon wafer to an another treatment step (hereinafter referred to as xe2x80x9cunloadingxe2x80x9d). More specifically, the silicon wafer is moved through the above opening portion, when loaded and unloaded. The container has a cover (i.e., lid) in a direction to the opening portion of the loader, which cover is opened when the silicon wafer is transferred into or out of the container.
When the silicon wafer is not transported, the opening portion of the loader is kept closed so as to prevent dust from floating into the high cleanliness room from the low cleanliness room. A door may be disposed in the opening portion so that the opening portion can be opened or closed by the door.
In this case, the door may be large enough to completely close the opening portion. In addition, the door may be the size in which the door is about 5 mm smaller in each side than respective side of the opening portion in such manner that there is provided aperture (open space) between the door and the opening portion, while the air pressure in the high cleanliness room is kept higher than that in the low cleanliness room, thus air flows through the aperture from the high cleanliness room to the low cleanliness room.
The following standards for the above container and loader are proposed and applied: SEMI (Semiconductor Equipment and Material International) Standard E47.1 [Box/Pod (FOUP)], E15.1[Tool Load Port], E57[Kinematic Coupling], E62[Front-Opening Interface Standard (FIMS), E63 [Box/Opener to Tool Standard (BOLTS) and the like (hereinafter referred to as xe2x80x9cStandardxe2x80x9d).
The container with the dust free article received therein is transported in the low cleanliness room by hand or a robot. Then, the container is mounted on a loader disposed in the border portion between the high cleanliness room and the low cleanliness room by hand or a robot. The cover disposed in the frontal surface of the container is opened or closed by an opener mechanism installed in the loader, thus the opening portion of the container is connected to or shut off the high cleanliness room.
A positioning pin and a key are provided in the opener mechanism, and a positioning hole and a key hole are provided in the front side of the container. In opening the cover of the container, the positioning pin is inserted into the positioning hole, and then the key is inserted into the key hole, and then the key is turned so as to operate an lock mechanism installed in the cover of the container in such manner that a lock claw of the lock mechanism is released from a portion to be hooked which is disposed on an edge portion of the container in the opening portion. Then, the opener mechanism is relatively retreated while the positioning pin and the key are kept inserted, thus opening the cover.
However, the above-mentioned operation has not been successfully performed because the scale of the parts in the container vary slightly. More specifically, the opener mechanism which is made of metal and has mechanical construction, i.e., the positioning pin and the key has very small tolerance when manufactured (for example, xc2x10.01 mm), whereas the body or the cover of the container is made of resin and has a relatively large tolerance when manufactured (for example, at least xc2x10.5 mm).
Furthermore, since the material of the container has elasticity so as to cause the whole body of the container to be deflected downward, there exist the following problems:
A. The container is deflected against the metal base portion which is directly placed on the loader in such manner that the location of the positioning hole slightly varies to cause the positioning pin to fail to enter into the positioning hole.
B. Even though the positioning pin is successfully inserted into the positioning hole, the key fails to be entered into the key hole. The reason thereof is that the relative relationship of the positioning hole and the key hole changes slightly. More specifically, if the relative relationship thereof changes only 0.4 mm, the key is not successfully inserted into the key hole.
C. The cover which closes the opening portion of the container is dislocated and lowered by the weight thereof, thus further causing the problems described in items A an B above to occur.
In order to overcome the problem described in item A above, (1) the inner diameter of the positioning hole 65 is made larger than the outer diameter of the positioning pin 39 so as to provide a larger play E (refer to FIG. 13). However, If the larger play E is provided, the cover is deflected downward by the same amount as the play E by the weight thereof, when the cover is opened. Accordingly, it is not easy to fittingly close the cover again.
Furthermore, in order to overcome the above-mentioned downward dislocation (i.e., downward movement) of the cover, there is proposed a technique in which a rubber cap 40 is provided around the positioning pin 39 so that the air inside the rubber cap 40 is sucked to be in a reduced pressure so as to support the cover 33, thus preventing the cover from deflecting downward (refer to FIG. 2). However, since the rubber cap 40 also has elasticity, the rubber cap does not satisfactorily function to support the cover.
In addition, in order to overcome the problem described in item A above, (2) chamfering is implemented on an edge of the positioning hole 65, and the amount of play is reduced (refer to FIG. 14), so as to prevent the cover from being lowered when opened. However, the tip portion of the positioning pin 39 is caught by the tapered surface of the chamfering 66 in such manner that the positioning pin is not successfully inserted.
The present invention is made to overcome the above-mentioned problems. The purpose of the invention is to provide a container in which the cover is prevented from being dislocated downward when opened, and the positioning pin as well as the key are successfully inserted into the positioning hole and the key hole respectively, even though the size of the parts in the container slightly varies.
In order to attain the above object, there is provided a following invention.
There is provided a first invention, which is a container for receiving and transporting dust free articles which is mounted on a loader installed in a border between a high cleanliness room and a low cleanliness room, an opening portion of which is connected to or disconnected from said high cleanliness room by opening and closing of a cover of said container by means of an opener mechanism arranged in said loader, which includes:
(a) a positioning hole provided in a front side of said cover into which a positioning pin of said opener mechanism is inserted; and
(b) a tapered surface formed only upper surface of inner portion of said positioning hole for enabling said cover to move slightly upward by means of contacting with said positioning pin.
According to the above-mentioned container, compared to the conventional art in which the larger play of the positioning hole is provided, the cover is opened in a state in which the cover is kept pushed upward by the function of the tapered surface, thus the cover is never dislocated downward. Furthermore, since the tapered surface is formed only on the upper surface of the inner portion of the positioning hole, the cover is surely moved upward in a slight amount, so that the positioning pin is surely inserted without being caught.
There is provided a second invention, which is the container, wherein said positioning hole has a double structure comprising a first hole formed as one unit with said cover in said front side of said cover, and a float received in said first hole in such manner that said float is movable in a slight amount at least vertically, on a front side of which float a second hole is formed into which said positioning pin is practically inserted, with said tapered surface formed on an upper inner surface of said second hole.
According to the above-mentioned container, when the positioning pin is inserted into the second hole of the float, the float contacts with the upper surface 155 of the first hole, and the cover is firmly pushed upward because of the momentum of the proceeding positioning pin. Thus, the positioning pin is prevented from being caught by the upper surface of the second hole.
Furthermore, the float firmly contacts with the upper surface of the first hole so that even if dust is produced by the friction between the float and the upper surface of the first hole, the dust is contained within the first hole, thus preventing the surrounding environment of the container from being contaminated.
In addition, when the cover is in a normal position in a state in which the cover is kept closed, the cover is not pushed upward by the float, and then the cover is dislocated downward in a slight amount when the cover is opened. However, the downward movement of the dislocation is caused only between the float and the first hole, thus the dust produced by the downward movement of the dislocation does not contaminate the surrounding of the container.
There is provided a third invention, which is the container, wherein a key hole portion having a key hole is provided on said front side of said cover into which a key of said opener mechanism is inserted, and a floating mechanism is provided to enable to move said key hole portion in a slight amount along a surface of said cover.
According to the above-mentioned container, even if the relative position of the key and the key hole, as well as the positioning pin and the pin hole vary, the key hole can slightly move by means of the floating mechanism so as to enable the key to be inserted into the key hole. In the present invention, the floating mechanism includes the mechanism using parts having elasticity.
There is provided a fourth invention, which is the container, wherein said floating mechanism has a structure in which a peripheral portion of said key hole portion is supported by a plurality of flat springs bent in J shape.
There is provided a fifth invention, which is the container, wherein said cover includes a lock mechanism for operating to close and open said cover by means of turning said key, and a lock claw of said lock mechanism, which is protruded from a window provided on an edge portion of said cover to engage with an engaged portion provided on an edge portion of said opening portion of said container, an inner flange and an outer flange being formed respectively in inner side and outer side of said edge portion of said opening portion, said engaged portion and a sealed area being disposed in between said inner and outer flanges.
According to the above-mentioned container, even if the dust is produced by the slight upward movement of the cover which causes friction between the engaged portion and the sealed area, the dust can be contained within the inner flange 131 and the outer flange 133.
There is provided a fifth invention, which is the container, wherein a tapered surface is formed on an inner upper surface of said first hole which enable said cover to move upward in a slight amount by means of contacting with said float.
According to the above-mentioned container, since the cover is pushed upward by the contact with the tapered surfaces, the friction is distributed between two tapered surfaces, and the dust produced by the contact between the tapered surface of the first hole can be contained within the float and the first hole.